Transcript Slide 1

Chapter 1
Part 1
Pages 5-26
PREANESTHETIC PERIOD
While the preanesthetic period
refers to the period immediately
proceeding the induction of
anesthesia, preparation for surgery
can begin long before an animal is
anesthetized.
Some PREANESTHETIC
responsibilities of a technician
include:
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obtaining patient history
reviewing consent form with an owner
making sure the patient is fasted
performing a physical exam
drawing blood and running diagnostic tests
placing an IV catheter
calculating drug doses
administering premedications
preparing anesthesic equipment
Feeling overwhelmed?
NO TWO PATIENTS ARE
ALIKE!!!!
Anesthesia is NOT a cookie cutter
procedure. Age, breed, size, and
health status are some of the factors
that can play into the selection of
anesthetic agents and techniques.
MINIMUM DATA BASE
Information used to evaluate a patient’s
readiness for anesthesia is gathered into a
MINIMUM DATA BASE which varies with
each clinic/veterinarian/patient, but should
ideally include:
HISTORY, PROCEDURE TO BE
PERFORMED, PHYSICAL EXAM,
DIAGNOSTICS and CONSULTATION TO
DETERMINE PHYSICAL STATUS AND
ANESTHETIC RISK
FASTING
• Fasting usually begins the night before surgery.
WHY FAST?
• Fasting is done to avoid vomiting/regurgitation during surgery
or recovery which can cause esophagitis, respiratory
obstruction, or aspiration pneumonia.
HOW LONG SHOULD THE FASTING PERIOD BE?
• Adult dog or cat: Withhold food for 8-12 hours before surgery.
Water is withheld anywhere from 2-10 hours before surgery,
depending on the veterinarian’s preference.
• Pediatric patients less than 3 months or less than 4 pounds:
Much shorter fasting period (depending on species, could be 46 hrs, or no fasting) to avoid dehydration or hypoglycemia.
• GI surgery: Withhold food for 24 hours, water for 8-12 hours.
• In addition to not fasting long enough, it is not safe to
have animals fasted for too long.
– This usually refers to animals refusing to eat for various
reasons - usually when the surgery is not elective: serious GI
obstructions/perforations, or in the situation where 2
surgeries are performed several days apart and the animal
does not want to eat in between the surgeries.
• This leads to a longer recovery period, delays
healing, and puts the animal at risk for other medical
problems (hepatic lipidosis).
• Options include hand/syringe feeding, inserting
feeding tubes, or total parenteral nutrition.
HISTORY TAKING
ALWAYS LOOK FOR WAYS TO
MODIFY YOUR METHOD.
LEARN FROM YOUR EXPERIENCES.
LIMIT POSSIBLE YES OR NO QUESTIONS –
THEY PROVIDE LITTLE INFORMATION!
EXAMPLE: Instead of asking “Does your dog drink a lot of water?”, ask “How much water
does your dog drink daily?”.
DON’T ASK LEADING QUESTIONS!
EXAMPLE: Don’t ask “Your dog doesn’t drink much, does he?”
ALLOW THE CLIENT TO ANSWER,
DON’T UNKNOWINGLY GUIDE THEM
TO AVOID/CHOOSE
ABNORMAL/NORMAL ANSWERS.
YOU WILL GET A
MORE TRUTHFUL EVALUATION.
So what questions should I ask?
• What procedure(s) is/are being performed today?
• How old is your animal?
• Is there a history of previous
illnesses/problems/treatment and if so, do you have
past medical records?
• Is your pet currently ill?
• What medications has your pet been on?
• Does your pet have any allergies or a history of drug
reactions?
• Has your pet had any previous anesthetic problems?
• Is your pet current on vaccines?
• Is your pet in heat or pregnant?
CONSENT FORM
• Have the client sign a consent form/estimate.
• This should be done in person. By phone is
an option, although this is not ideal. Make
sure a witness also hears the authorization.
• A consent form reviews anesthetic risks,
resuscitation options, blood work options, and
phone numbers for the owner.
• Some forms also state that a drug will be
used on their animal in an extra-label
manner.
* If possible, have the owner read the estimate and
consent form before the day of surgery.
PHYSICAL EXAM
The physical exam is done by a veterinarian,
but a technician can also perform an
exam. This can easily been done when
drawing blood for diagnostics.
POINT OUT WHAT YOU FIND (EVEN
WHAT MAY SEEM OBVIOUS) AS
SOME THINGS ARE EASILY
OVERLOOKED ON A BUSY
SURGERY DAY. Write down your
findings and also tell them to the
doctor.
SIGNALMENT: species, breed, weight, age,
sex, reproductive status
THIS IS HOW EVERY ANIMAL’S HISTORY
SHOULD BEGIN
Example: “Tiny is a 4 year old intact female Pug who
weighs 33 pounds.”
THE SIGNALMENT HAS A LOT OF
IMPORTANT INFORMATION
SPECIES AND BREED
• Usually don’t have to say the species if the breed
makes it obvious
• Doses are different between species and are listed
accordingly in drug manuals. NEVER ASSUME that
the dose for one species will be the dose for another.
Each animal will respond differently to various
drugs and have different anesthetic needs
Example: Thiopental is an injectable induction agent that usually
has a short recovery time because it is highly lipid soluble,
meaning it moves quickly from brain to muscle and then to fat.
Sighthounds have a low amount of fat, so the drug remains in
effect for a longer period of time.
Tiny is a Pug- what anesthetic
concerns exist for this breed?
Brachycephalic breeds are at risk for
having an elongated soft palate
which can make intubation and
recovery difficult.
WEIGHT
• Dosages are based on weight in addition
to species. DON’T ESTIMATE. Weigh
accurately.
• Use a pediatric scale (if available) if less
than 15 kg – will read pounds and ounces.
• Compare current weight to previous
weights.
• IV fluid rates are also weight based.
WEIGHT CONT’D….
OBESE ANIMALS can
experience dyspnea, they can be
difficult to draw blood from,
harder to assess hydration status, and
difficult to auscultate any abnormalities.
THIN ANIMALS can be at risk
for hypothermia and may have
an underlying condition causing
weight loss.
AGE
• VERY YOUNG ANIMALS (usually less than
8 weeks) are less capable of metabolizing
injectable drugs because the liver is not
fully developed and most
biotransformation occurs in the
liver.
• GERIATRIC ANIMALS may have poor
organ function and may not be able to
properly handle the metabolism. This
leads to a potentially slow recovery.
REPRODUCTIVE STATUS
• Is there a possibility of pregnancy?
Affects which drugs are used – want minimal
affect on fetuses
• Are both testicles descended? Affects
clip, prep, surgery
• Always check females for evidence of a
spay scar or tattoo
SEX
ALWAYS BE SURE THAT THE FEMALE
CAT WHO ARRIVES TO BE SPAYED
IS ACTUALLY A FEMALE!
No one wants to spay a male!
BEYOND SIGNALMENT
DISPOSITION AND ACTIVITY LEVEL
• Anxious or aggressive animals
may require a combination of
drugs for sedation, or more
potent medications.
• Fearful or aggressive animals may require
a different route of medicine
administration (ex: oral,
induction chamber)
ASSESSING HYDRATION STATUS
PHYSICAL
FEATURE
5% (mild)
DEHYDRATED
6-9% (moderate)
DEHYDRATION
10-12% (profound)
DEHYDRATION
EYELID PINCH
MILD TENTING;
PINCH SLOWLY
RELAXES
SEVERE TENTING;
PINCH PERSISTS
SEVERE TENTING;
PINCH PERSISTS
CORNEA
CORNEA MOIST;
TEARING STILL
POSSIBLE
CORNEA DRIER;
TEARING
INFREQUENT
DRY CORNEA; NO
TEARING
EYEBALL
POSITION IN ORBIT
MINIMAL SPACE
BTW. MEDIAL
CANTHUS AND
GLOBE (1-2mm)
PRONOUNCED
SPACE BETWEEN
(2-4 mm)
SPACE IS LARGER
THAN 4 mm
SKIN ON NECK
DECREASED
PLIABILITY
TENTED SKIN
PERSISTS 3-5 sec
TENT PERSISTS > 5
sec
ORAL MUCOUS
MEMBRANES
MOIST, WARM,
PINK
WARM, STICKY,
PALE
DRY, COLD,
CYANOTIC OR
PALE. POOR CRT
GENERAL
CONDITION
STANDING;
EXTREMETIES ARE
WARM
OFTEN
RECUMBENT
OFTEN MENTALLY
DULL,
EXTREMITIES
COLD, RAPID
PULSE
LAB FINDINGS
NORMAL
INCREASED PCV
AND TOTAL
PROTEIN,
DECREASED
URINE VOLUME
SAME
Ideally, dehydration should be corrected
prior to surgery.
(Wt in kg)(1000 mL/kg)(% dehydration)
EXAMPLE:
A 33 lb dog that is 9% dehydrated, needs
_______mL
33 lb /2.2 = 15 kg
(15 kg)(1000 mL/kg) = 15,000 mL
(15,000 mL)(0.09) = 1350 mL
HEAD
ORAL CAVITY
- Breathing noises can indicate an anatomical problem.
- Check gum color and capillary refill time (CRT)
- NOTE: Animals with pigmented gums can still be
analyzed. Look at conjunctiva, inner vulva, prepuce
to assess.
http://www.infovets.com/demo/demo/canine/B105.HTM
HEAD cont’d
• Look at the ears and nose for any signs of growths,
infection, or ear mites
EYES
• Observe not only for signs of dehydration, but also
look at pupillary reflexes (help localize the lesion –
nerves vs. eyes. vs. brain)
– NOTE: Some anesthetics or excitation will alter this.
AUSCULTATION
RATE
RHYTHM
ABNORMAL SOUNDS
DOGS
= 60-180 bpm
(breed dependent)
= 10-30 bpm
CATS
= 110-220 bpm
= 25-40 bpm
Age and excitement,
in addition to
medical conditions,
can alter rate
Listen for
normal
sinus rhythm
versus
arrhythmias
Listen for murmurs,
crackles, wheezes,
and extra heart beats.
Look for open-mouthed
breathing, flared nostrils,
excessive panting, abdominal
breathing, stance, and cyanosis
Listen to all 4 quadrants
of chest and all 4 valves.
Cat murmurs are often
sternal in location.
PULSE
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Assess the strength and rate
The femoral artery on the medial aspect of
the hind leg is the easiest location to palpate
Can also use the metatarsal/metacarpal
artery, sublingual artery, dorsal pedal artery
Strong/weak pulse correlates with blood
pressure
Pulse deficits = heart disease
OTHER THINGS TO LOOK FOR:
• BODY TEMPERATURE: N = 99.5•
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102.5°F
LIMBS: look for signs of pain/lameness
LYMPH NODES: Are they palpable? Are they
firm?
ABDOMINAL PALPATION: feel for
abnormalities in organ size, location, fluid or
gas within abdomen, fetuses, feces
MAMMARY GLANDS: Are they engorged?
Are there lumps? Is the animal lactating?
PREPUCE/VULVA: Look for anatomical
abnormalities and discharge
DIANOSTIC TESTS
• The extent of Diagnostic Testing
performed as part of the MINIMUM
DATA BASE depends on the clinic
policy, owner consent, and what is ideal
for the animal.
• It is important to provide the most
complete and affordable testing
available, depending on the clinic.
• PCV and RBC
– used to determine the blood’s ability to deliver oxygen to
tissues. Increases usually indicates dehydration (which leads
to increased viscosity of the blood, poor perfusion and
decreased cardiac output). Decreased levels usually
indicates anemia.
• TOTAL PLASMA PROTEIN
– usually indicates dehydration if increased or a loss through
the renal, hepatic or GI systems if decreased. Decreased
levels can lead to drug potency.
• BLOOD SMEAR
– used to evaluate red blood cells, white blood cells, and
platelets grossly.
URINALYSIS
• SPECIFIC GRAVITY
– used to detect evidence of dehydration or renal insufficiency
• GLUCOSE and KETONES
– used to detect diabetes
• WBCs and RBCs
– can be seen with urinary tract infections and crystalluria
(can also be normal in small amounts)
• USE THESE RESULTS IN CONJUNCTION WITH OTHER TESTS
CHEMISTRY PANEL
MOST COMMONLY EVALUATED
PARAMETERS PRE-OPERATIVELY
ARE:
ALP, ALT, BUN, CREATININE,
GLUCOSE, ELECTROLYTES
The more parameters that are
evaluated, the better picture we have
of the patient.
CLOTTING TIMES
• Not commonly performed for routine
procedures unless coagulopathies are
suspected.
• In-clinic testing is performed by either
performing a Buccal Mucosal Bleeding Time
(BMBT), a short nail trim to the quick, or
placing whole blood in a plain red top. Blood
should clot within 4 minutes.
ECG
Evaluates electrical activity, pattern,
rhythm, size, and shape
• Do if heart disease is suspected,
there is a history of trauma,
electrolyte abnormalities, or if the
animal is geriatric
RADIOGRAPHS are not routinely done in
private practice, but are indicated with
dyspnea, abnormal heart/lung sounds,
or history of recent trauma.
HEARTWORM TEST – it is important to
know heartworm status before
undergoing anesthesia
ANESTHETIC STATUS
• Classification based on history,
physical exam, and diagnostics
performed
• Classification is objective and can
change with animal’s status
• Correct problems before surgery if
possible
Category
Physical condition
Examples
Class I
Minimal risk
Normal, healthy animal
w/o underlying disease
Spay, neuter, declaw, hip
rads
Class II
Slight risk, minor
disease
Slight to mild systemic
disturbances; animal
compensate
Neonates, geriatric,
obese, skin tumors,
uncomplicated hernia,
local infection
Class III
Moderate risk, obvious
disease
Moderate systemic
disease, mild clinical
signs
Anemia, moderate
dehydration, fever, lowgrade murmur or heart
disease
Class IV
High risk, significant
disease
Preexisting systemic
disease
Severe dehydration,
shock, uremia, high fever,
severe heart or lung
disease, diabetes,
emaciation
Life threatening disease
Class V
Extreme risk, moribund that may not be corrected
by surgery, animal may
not survive 24 hrs
Advanced heart, liver,
kidney, lung, or terminal
disease, severe shock,
head injury, severe
trauma
2yr old, mixed breed intact male weighing 12lbs; BCS: 2/5,
T-103.5, HR-160, RR-40; 8% dehydrated
Bloodwork: PCV: 35%, TP: 7.6 g/dl
What anesthetic status would you give this dog?
Preanesthetic Pic of the Day
Based on the picture, what anesthetic
category would you place
Oscar in?